Higher heat and humidity causing brown patch

Published 12:00 am Sunday, May 26, 2019

Many fescue lawns looked perfect earlier, but brown circles are beginning to be tainted yellow, dead circles.

With warmer temperatures and humidity, brown patch has arrived. Temperatures above 80 degrees, coupled with high humidity provides the perfect environment for the development of this disease. Early symptoms are small circular brown patches of turf a foot in diameter. Small patches often melt together and may engulf an entire area of a lawn.

Several factors listed below promote this fungal disease outbreak.

     • Late fertilization in the spring. The recommended amount of nitrogen on tall fescue per year is 3-4 pounds per 1,000 square feet. Never fertilize fescue past mid-April.

     • Over-seeding produces small, crowded seedlings with poor root systems that are also susceptible to brown patch.

      • A low soil pH below 6.0 aggravates the spread of brown patch. Now is the time to have soils tested if fall renovation is in your plans.

     • Over irrigating. The most important step of controlling brown patch is infrequent irrigation and regular mowing when the grass is dry. Avoid irrigation in the late evening or at night. Early morning irrigation helps prevent the spread of brown patch.

There are fungicidal control measures for this cool season lawn fungal disease, but they can be costly and often applied too late. These preventative fungicides must be applied now.

More detailed information can be found at https://www.turffiles.ncsu.edu/diseases-in-turf/brown-patch-in-turf/

Darrell Blackwelder deblackw@ncsu.edu is the retired horticulture agent with the North Carolina Cooperative Extension Service in Rowan County.